It is known in the art relating to top feed engine fuel injectors to provide a well or cup shaped filter element retained within an inlet tube between its entrance end and the end of an associated adjusting tube. One prior conventional form of filter mounting consists of a well (or deep cup) shaped screen element connected at its open end to a brass ring that is pressed into the open end of the injector inlet tube. The screen portion of the filter element is spaced from the inner end of the associated adjusting tube. Fuel flows into the open end of the cup or well shaped element and out through the sides and bottom thereof into the hollow adjusting tube. Other forms of prior filter arrangements are shown in U.S. Pat. Nos. 5,335,863 issued Aug. 9, 1994 and 5,356,079 issued Oct. 18, 1994, both to the assignee of the present invention.
Another arrangement is shown in FIG. 1 of the drawings where there is illustrated for reference a prior art engine fuel injection system generally indicated by numeral 10. Injection system 10 includes a fuel rail 12 defining a passage for the delivery of fuel from a fuel source not shown. At spaced locations along the fuel rail there are provided a plurality of fuel rail cups 14, only one of which is shown. Each cup 14 includes a base 16 secured to the fuel rail and having an inturned edge defining a central port 18 through which fuel may flow from the interior fuel rail to the cup. The cup 14 further includes a cylindrical flange 20 depending from the base and forming with the base a recess open through the port 18 to the fuel rail.
A conventional top feed fuel injector generally indicated by numeral 22 includes a fuel inlet tube 24 having an entrance end 26 that is received within the cup 14 spaced axially from the port 18. An upper O-ring seal 28 retained adjacent the end of the inlet tube 24 engages the flange 20 of the cup to seal the connection against fuel leakage. A clip 30 secured to the injector housing 32 has a slot that engages an outturned end of the flange 20 to retain the injector in place in the cup 14.
Injector 22 includes a body 34 having a central axis 36 and including the inlet tube 24 and housing 32 centered on the axis 36. An adjusting tube 38 is telescopingly received within the inlet tube and engages at an inner end a spring 40 which in turn engages an armature 42 reciprocally movable within the body 34. The armature carries a valve needle 44 that extends through a needle guide 46 into engagement with conical surfaces of a valve seat 48 retained within the lower end of a valve body 50.
A magnetic coil 52 mounted in the injector body 34 surrounding the inlet tube 24 is positioned to attract the armature 42 when energized, moving the armature slightly against the bias of spring 40 and unseating the valve needle 44 from the seat 48. This allows fuel to flow along a fuel path from the interior of the fuel rail 12 through the port 18 into the entrance end of the fuel inlet tube 24. The fuel passes on through the adjusting tube 38 and spring 40 to an opening 54 in the armature 42 that allows the fuel to flow around the valve needle 44. It then is directed through openings 56 in the needle guide 46, past the end of the valve needle 44 and through an orifice 58 in the valve seat. The fuel then moves through an opening 60 in a backup washer 62 and out through the nozzle end of the injector into an associated cylinder head or inlet manifold not shown. An electrical connector 64 conducts electric current for energizing the magnetic coil 52 when desired.
In the illustrated prior art embodiment, the interior of the inlet tube 24 adjacent the entrance end is enlarged to receive yet another form of inlet fuel filter generally indicated by numeral 66. Filter 66 has a closed upper end 68 having a tubular screen mesh portion 70 below with an open lower end mounted on a filter connector 72. The filter connector has latching fingers 74 engaging a groove 76 near the inlet end of the adjusting tube 38 to retain the filter 66 on the inlet end of the adjusting tube and recessed within the end of inlet tube 24. The screen mesh portion 70 of the filter separates out particulates in the fuel entering the inlet tube to prevent their continued passage through the injector and into the engine in known manner.
With the exception of the embodiment of FIG. 2 of U.S. Pat. No. 5,356,079, the prior filter arrangements referred to all utilize a well or cup shaped filter element retained within the inlet tube between its entrance end and the end of the associated adjusting tube. These arrangements require space for the length of the filter element which adds to the required length of the inlet tube and therefore the overall length of the injector in the fuel injector system.